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(11) | EP 2 348 626 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Switching power supply with surge voltage suppression |
(57) A switching power supply unit receiving a DC input voltage (10) from one of first
and second input/output terminal pairs (T1,T2) and outputting a DC output voltage (V out) from the other input/output terminal pair, comprising: a transformer (3) including a first winding disposed on the first input/output terminal pair side and a second winding disposed on the second input/output terminal pair side; a first circuit (1) disposed between the first input/output terminal pair and the transformer, and including a plurality of first switching elements and first rectifier elements each of which is connected in parallel with each of the plurality of first switching elements; a second circuit (4) disposed between the second input/output terminal pair and the transformer, and including a plurality of second switching elements and second rectifier elements each of which is connected in parallel with each of the plurality of second switching elements; a surge voltage suppressing circuit (2) connected in parallel with the first circuit, and including two device sets each having a third rectifier element connected in a manner of reversed polarity and a first capacitative element, the third rectifier element and the first capacitative elements being connected in parallel with each other; a first inductor (Lr) disposed between the first input/output terminal pair and the transformer; a second inductor (S1) disposed between the second input/output terminal pair and the transformer; and a driving circuit (6) for driving each of the first and second circuits. |